JP2015100945A - Ink discharge device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink discharge device that discharges ink to a recording medium to form a print image, wherein the permeation of ink into the recording medium is properly controlled without causing an increase in cost and power consumption.SOLUTION: The ink discharge device has an ink head part 10 that discharges photocurable ink to recording medium, and a light source unit 15 that, before the photocurable ink discharged from the ink head part 10 impacts the recording medium, irradiates the photocurable ink with light.

Description

  The present invention relates to an ink ejection apparatus that ejects ink onto a recording medium.

  2. Description of the Related Art Conventionally, inkjet printers that form printed images by ejecting ink onto a recording medium such as printing paper have been proposed.

  In general, in an ink jet printer, as shown in FIG. 15, ink droplets that have landed on a printing paper are impregnated and soaked along the fiber of the paper, and in particular, printing with coarse fibers such as tissue paper, half paper, and Japanese paper. In the case of paper, the ink diffuses into the space between the fibers, and even if the diameter immediately after landing is small, the ink soaks into the surrounding fibers after the passage of time, and the dots become large and blur. There has been a phenomenon in which the so-called “dot gain” becomes thinner.

  On the other hand, there is a method of using a coated paper coated with a pigment such as calcium carbonate to make it difficult for the ink to spread on the surface of the printing paper. However, since coated paper is very expensive, there is a problem that it is not economical.

  Therefore, in Patent Document 1, ultraviolet curable ink that cures when irradiated with ultraviolet rays is used, and ultraviolet curing that has landed on the surface of the printing paper from the back side of the printing paper (the side opposite to the surface on which the ink is ejected). There has been proposed a method of suppressing ink permeation by irradiating the mold ink with ultraviolet rays.

JP 2011-98448 A

  However, when ultraviolet rays are irradiated from the back side of the printing paper as in the method described in Patent Document 1, ultraviolet rays that have passed through the printing paper are applied to the ink head to avoid ink clogging. Only ultraviolet rays could be applied to the ink, and in particular, the strength was insufficient to cure the ink droplet immediately after landing on the surface of the printing paper.

  Therefore, there still remains a problem that the ink droplets just after landing on the printing paper cannot be cured, and the surroundings are impregnated.

  In addition, if the ultraviolet rays are irradiated after the ink has landed on the printing paper, the ink will be hidden behind the fiber, and even if the ultraviolet rays are irradiated from the surface of the printing paper, the ultraviolet rays will not hit the ink. was there. In order to solve this problem, there is a method of irradiating a large amount of ultraviolet rays to transmit the fibers of the printing paper, but a very bright light source is required, resulting in an increase in cost and power consumption. .

  SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide an ink ejection apparatus that can appropriately suppress the penetration of ink into a recording medium without causing an increase in cost or an increase in power consumption. .

  An ink discharge apparatus according to the present invention includes an ink discharge unit that discharges photocurable ink toward a recording medium, and the photocurable ink before the photocurable ink discharged from the ink discharge unit lands on the recording medium. And a light irradiator for irradiating light.

  In the ink ejection device of the present invention, the light irradiation unit can irradiate light from a direction perpendicular to the ejection direction of the ink ejected from the ink ejection unit.

  In addition, the ink discharge unit discharges photocurable ink at a predetermined interval, and the light irradiation unit controls the light emission timing based on the discharge timing of the photocurable ink from the ink discharge unit. And can.

  Moreover, a light irradiation part can irradiate light from two opposing directions with respect to photocurable ink.

  In addition, the light irradiating unit may include a light source that emits light in one of two opposing directions and a reflecting unit that reflects the light emitted from the light source in the other direction.

  Further, a light shielding member that shields light can be provided around the photo-curable ink ejection port of the ink ejection unit.

  According to the ink ejection device of the present invention, the light curable ink ejected from the ink ejection section is irradiated with light before landing on the recording medium. Since a thin skin or gel film can be formed on the recording medium, it is possible to suppress the penetration of the ink when the ink lands on the recording medium. As a result, the dot size does not increase, the resolution does not decrease, and the density does not decrease, and high-quality printing can be performed even when paper having a low fiber density is used.

  In addition, since the light intensity is sufficient to form a thin film on the surface of the ink droplets, it is not necessary to use a light source with such a high light intensity. For example, an LED (Light Emitting Diode) can be used to reduce costs. It is possible to reduce power consumption.

  In addition, in the ink ejection device of the present invention, when light is emitted from a direction perpendicular to the ejection direction of the ink ejected from the ink ejection unit, the light ejection to the ink ejection unit is suppressed. As a result, clogging in the ink discharge portion can be prevented.

  In addition, when the light emission timing is controlled based on the discharge timing of the photocurable ink from the ink discharge portion, the light is irradiated at the timing when the ink droplet falls into the light irradiation range. As a result, the ink droplets can be efficiently irradiated with light.

  In addition, when light is applied to the photocurable ink from two opposing directions, a thin film can be formed on almost the entire surface of the ink droplet, so that ink penetration is further suppressed. Can do.

  In addition, when a light source that emits light in one of the two opposite directions described above and a reflection unit that reflects light emitted from the light source in the other direction are provided, Since the number of light sources can be reduced by the amount of use of the reflective portion as a substitute, cost can be reduced and power consumption can be suppressed.

  In addition, when a light blocking member that blocks light is provided around the discharge port of the ink discharge unit, it is possible to further suppress light irradiation to the discharge port and to prevent clogging in the ink discharge unit. .

The figure which shows the whole schematic structure of the inkjet printer using one Embodiment of the ink discharge apparatus of this invention. The figure which looked at the ink head part and light source part which are shown in Drawing 1 from the upper part Detailed configuration diagram of ink head and light source Diagram for explaining the effect of light irradiation on ink before landing The figure for demonstrating the effect by which the osmosis | permeation of ink is suppressed The block diagram which shows the structure of the control system of the inkjet printer shown in FIG. The figure for demonstrating the example which irradiates pulsed light Timing chart showing ink ejection timing from ink head, emission timing of ultraviolet rays from ultraviolet LED, and irradiation timing of ultraviolet rays to ink droplets The figure which shows the modification of the ink discharge apparatus of this invention The figure which shows the modification of the ink discharge apparatus of this invention The figure which shows the modification of the ink discharge apparatus of this invention The figure which shows the example which comprised the light source part from one ultraviolet LED and the fiber light guide part The figure which shows the example which comprised the light source part from one ultraviolet LED and a parabolic mirror Block diagram showing the configuration of the control system when the intensity of ultraviolet rays is changed according to the type of printing paper The figure which shows the mode of penetration of the ink to the printing paper in the conventional ink jet printer

  Hereinafter, an ink jet printer using an embodiment of an ink ejection apparatus of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram showing a schematic configuration of the entire inkjet printer 1 of the present embodiment. FIG. 2 is a view of the ink head unit 10 and the light source unit 15 shown in FIG. 1 as viewed from above.

  The ink jet printer 1 includes an ink head unit 10 (corresponding to an ink ejection unit), a light source unit 15, a paper transport unit 20, a paper feed unit 30, and a paper discharge unit 40.

  The ink head unit 10 performs printing processing by ejecting ink onto the printing paper P based on print job data and read image data. As shown in FIG. 2, the ink head unit 10 of the present embodiment includes line-type ink heads 10 a to 10 d that extend in a direction orthogonal to the conveyance direction of the printing paper P, and the ink heads 10 a to 10 d. Are for ejecting black K, cyan C, magenta M, and yellow Y inks, respectively. The colors d to 10d are arranged side by side with a predetermined interval in the conveyance direction of the printing paper P.

  And each ink head 10a-10d of the ink head part 10 of this embodiment discharges the photocurable ink hardened | cured by irradiation of light, and specifically, the ultraviolet curing type hardened | cured by irradiation of an ultraviolet-ray. Ink is used. The ultraviolet curable ink contains an ultraviolet curable resin such as a radical polymerizable resin composition and a cationic polymerizable resin composition as a main component. Among these resin compositions, a cationic polymerizable resin composition is preferable from the viewpoint of adhesion of the ink to the printing paper P, but a radical polymerizable resin composition is preferable from the viewpoint of curing speed and raw material cost. The radical polymerizable resin composition is suitable when speeding up and improvement in processing efficiency are required. Moreover, you may make it use the hybrid type ink containing both a cationically polymerizable resin composition and a radically polymerizable resin composition.

  The content of the ultraviolet curable resin is preferably 60 (mass%) to 95 (mass%), more preferably 80 (mass%) to 95 (mass%) with respect to the whole ink from the viewpoint of the viscosity of the ink. ) Is more preferable.

  Examples of the polymerizable resin component of the radical polymerizable resin composition include oligomers and monomers of (meth) acrylic acid-modified derivatives of various compounds such as urethane-based, epoxy-based, polyester-based, and polyol-based compounds, and unsaturated polyester compounds. And oligomers and monomers of aromatic vinyl compounds.

  In this embodiment, an ultraviolet curable ink that is cured by irradiation with ultraviolet rays is used. However, the present invention is not limited to this, and a photocurable ink that is cured by irradiation with light of other wavelengths such as infrared light and visible light is used. You may make it use.

  The light source unit 15 irradiates the photocurable ink in flight with light before the photocurable ink discharged from the ink heads 10 a to 10 d of the ink head unit 10 lands on the printing paper P. is there. As shown in FIGS. 1 and 2, the light source unit 15 is provided on each of the downstream side and the upstream side of the ink head unit 10, and has a height between the ink head unit 10 and the paper transport unit 20. It is arranged. Specifically, each light source unit 15 of the present embodiment has a plurality of ultraviolet LEDs emitting ultraviolet rays arranged in a direction orthogonal to the conveyance direction of the printing paper P. As shown in FIGS. 1 and 2, the light source unit 15 disposed on the downstream side emits ultraviolet rays L1 toward the upstream side, and the light source unit 15 disposed on the upstream side is disposed on the downstream side. The ultraviolet ray L1 is emitted toward. As the ultraviolet LED, a known LED can be used, for example, OSV5XME1C1 manufactured by Optosupply Limited.

  FIG. 3 is a diagram illustrating a detailed configuration of each of the ink heads 10 a to 10 d and the light source unit 15 of the ink head unit 10. In FIG. 3, only the yellow Y and black K ink heads 10a and 10d are shown, and the cyan C and magenta M ink heads 10b and 10c are not shown, but the cyan C and magenta M inks are omitted. The heads 10b and 10c have the same configuration as the yellow Y and black K ink heads 10a and 10d shown in FIG.

  As shown in FIG. 3, each of the ink heads 10 a to 10 d includes an ink chamber 11 in which ultraviolet curable ink is filled, and an ejection port 12 from which the ultraviolet curable ink filled in the ink chamber 11 is discharged. Yes. A large number of ink chambers 11 and ejection openings 12 are arranged in a direction orthogonal to the transport direction of the printing paper P.

  In addition, a light shielding member 13 that shields ultraviolet rays emitted from the light source unit 15 is provided around the row of the ejection ports 12 arranged in a direction orthogonal to the conveyance direction of the printing paper P. The light shielding member 13 is made of a member that absorbs ultraviolet rays, and is provided along the length direction on both sides of the row of the ejection ports 12. The height H from the discharge surface of the light shielding member 13 is set to such an extent that the light emitted from the light source unit 15 is not directly irradiated to the discharge port 12.

  In addition, a reflection member 14 that reflects ultraviolet rays emitted from the light source unit 15 is provided on the surface of the light shielding member 13 on the side of the paper conveyance unit 20. Similarly to the light blocking member 13, the reflecting member 14 is also provided along the length direction on both sides of the row of the ejection ports 12.

  As described above, by providing the light shielding member 13 and the reflecting member 14 around the ejection port 12 of the ink head, the ultraviolet rays emitted from the light source unit 15 are irradiated to the ejection port 12, thereby causing the ink near the ejection port 12 to be ejected. It is possible to prevent clogging due to curing.

  Specifically, the light source unit 15 has a number of ultraviolet LEDs 15a arranged in a direction orthogonal to the transport direction of the printing paper P, and a refractive index distribution type that emits the ultraviolet rays emitted from the ultraviolet LEDs 15a as parallel light. And a lens array 15b. The gradient index lens array 15b has a large number of gradient index lenses arranged along the row of ultraviolet LEDs 15a. The ultraviolet rays L1 converted into parallel light by the gradient index lens array 15b are applied to the flying ink droplets ejected from the ejection port 12 of the ink head. Thus, clogging of the discharge port 12 can also be prevented by making the ultraviolet ray L1 parallel light.

  Then, as shown in FIG. 4, the ultraviolet light L1 emitted from the ultraviolet LED 15a of each light source unit 15 is irradiated onto the flying ink droplet before landing, whereby the surface of the ink droplet (shown by a dotted line in FIG. 4). ), A thin film having a thickness of about 0.05 μm to 0.5 μm can be formed. Therefore, as shown in FIG. 5, after the ink droplets have landed on the printing paper P, the penetration of the ink can be suppressed. As a result, the dot size increases, the resolution decreases, and the density decreases. Therefore, even when paper having a coarse fiber density is used, high-quality printing can be performed.

  Returning to FIG. 1, the paper feeding unit 30 feeds the printing paper P to the ink head unit 10. The paper feed unit 30 includes a paper feed tray 31 on which the print paper P is placed, a pickup roller 32 that picks up the print paper P placed on the paper feed tray 31, and a front end of the print paper P that is picked up by the pickup roller 32. After stopping and correcting skew, a registration roller 33 that transports the printing paper P toward the paper transport unit 20 at a predetermined timing and a plurality of motors (not shown) that drive the rollers are provided. Yes.

  The paper transport unit 20 is provided below the ink head unit 10, and includes a transport belt 21 that transports the printing paper P supplied from the registration rollers 33, a transport roller 22 that moves the transport belt 21, and a transport roller. And a motor (not shown) for driving the motor 22.

  The paper discharge unit 40 discharges and stacks the printed printing paper P conveyed by the paper conveyance unit 20. The paper discharge unit 40 includes a paper discharge roller 41 that conveys the printed print paper P, a paper discharge tray 42 that discharges and stacks the print paper P transported by the paper discharge roller 41, and a paper discharge roller 41. And a motor (not shown) for driving the motor.

  Next, the control system 50 of the inkjet printer 1 of the present embodiment will be described with reference to FIG. The control system 50 of the ink jet printer 1 according to the present embodiment includes a paper conveyance control unit 51, an ink discharge control unit 52, and a light source control unit 53.

  The paper conveyance control unit 51 controls the motors that drive the rollers in the paper feeding unit 30, the paper conveyance unit 20, and the paper discharge unit 40, and controls the conveyance timing and conveyance speed of the printing paper P, etc. To do.

  The ink discharge control unit 52 controls the ink discharge timing from each of the ink heads 10a to 10d according to the transport position of the printing paper P. Ink droplets are ejected from each of the ink heads 10a to 10d, and dots are formed when the ink droplets land on the printing paper P. The density and gradation of the printed image are controlled by controlling the number of ink droplets forming one dot.

  The light source control unit 53 supplies a drive voltage to the ultraviolet LED 15a, and controls the drive current flowing through the ultraviolet LED 15a by controlling the drive voltage, whereby the emission timing of ultraviolet rays from the ultraviolet LED 15a and the ultraviolet rays are controlled. It controls the intensity of the. In the present embodiment, the light source unit 15 and the light source control unit 53 correspond to a light irradiation unit.

  As shown in FIG. 7, the light source control unit 53 of the present embodiment can change the duty ratio of the drive voltage supplied to the ultraviolet LED 15a, thereby supplying the drive voltage having a pulse waveform to the ultraviolet LED 15a. In addition, the ultraviolet LED 15a can be pulse-lit.

  Here, when the duty ratio of the driving voltage is 100%, the ultraviolet LED 15a is continuously lit, but in this case, the lifetime of the ultraviolet LED 15a is shorter than when the ultraviolet LED 15a is pulse-lit.

  Therefore, from the viewpoint of the lifetime of the ultraviolet LED 15a, it is desirable to pulse the ultraviolet LED 15a. Further, when the ultraviolet LED 15a is pulse-lit in this way, the intensity of the ultraviolet light (the amount of light per unit time) can be increased, so that the curing of the ink can be promoted. For example, when the duty ratio is 25%, the intensity of ultraviolet rays can be quadrupled.

  However, in the present embodiment, since ultraviolet rays are irradiated to the ink droplets in flight before landing on the printing paper P, the longer the emission time of the ultraviolet rays from the ultraviolet LED 15a, the more efficiently the ultraviolet rays are irradiated to the ink droplets. From this point of view, it is desirable to continuously turn on the ultraviolet LED 15a.

  Further, from the viewpoints of both the lifetime of the ultraviolet LED 15a as described above and the improvement in the efficiency of irradiation of the ultraviolet rays onto the ink droplets, the ultraviolet LED 15a is pulse-lit and the emission timing of the ultraviolet rays is set based on the ink ejection timing. You may do it.

  FIG. 8 is a timing chart showing ink ejection timings from the respective ink heads 10a to 10d, ultraviolet ray emission timings from the ultraviolet LED 15a, and ultraviolet ray irradiation timings on the ink droplets. Here, the timing is controlled so that the ultraviolet rays are emitted from the ultraviolet LED 15a when the ink droplets ejected from the ink heads 10a to 10d fall into the ultraviolet irradiation range of the ultraviolet LED 15a. That is, as shown in FIG. 8, after the ink droplets are ejected from the respective ink heads 10a to 10d, ultraviolet rays are emitted from the ultraviolet LED 15a when a predetermined time T elapses. The time T is a distance D1 from the ink ejection surface of each of the ink heads 10a to 10d as shown in FIG. 3 to the ultraviolet irradiation range (center position), and the position of the ink head unit 10 from the ultraviolet emission surface of the light source unit 15 ( And a distance D2 to the center position). Specifically, for example, T = (distance D1 / ink droplet drop speed) + (distance D2 / light speed) may be set. In addition, when the drop speed of the ink droplet is 2 m / s to 10 m / s and the distance between the ink head unit 10 and the printing paper P is about 15 mm, the ink is applied for 1.5 ms to 7.5 ms. Since the droplets fly, ultraviolet rays are irradiated during this time.

  By setting the time T in this way, the ultraviolet rays are emitted from the ultraviolet LED 15a when the ink droplets ejected from the ink heads 10a to 10d fall into the ultraviolet irradiation range, and this is irradiated onto the ink droplets. be able to. Thereby, the surface of the ink droplet can be appropriately cured. As a method for calculating the time T, a calculation method other than the above may be used.

  In the above embodiment, the light source unit 15 is provided on the upstream side and the downstream side of the ink head unit 10. However, the present invention is not limited to this. For example, as illustrated in FIG. 9, the downstream side of the ink head unit 10. Alternatively, a reflection mirror 60 (corresponding to a reflection portion) that reflects the ultraviolet light L1 emitted from the upstream light source unit 15 may be provided. Even with such a configuration, it is possible to irradiate the ink droplets with ultraviolet rays from both sides. In contrast to the arrangement shown in FIG. 9, the light source unit 15 may be provided on the downstream side, and the reflection mirror may be provided on the upstream side.

  Further, as shown in FIG. 10, a fixing light source unit 70 may be further provided on the downstream side of the ink head unit 10 for curing and fixing the ink after landing on the printing paper P. The fixing light source unit 70 may be composed of an ultraviolet LED similarly to the light source unit 15.

  Further, in the above embodiment, the direction perpendicular to the ejection direction of the ink droplets ejected from each of the ink heads 10a to 10d, that is, the direction in which the ink droplet falls is the downward direction, and the opposite direction is the upward direction. Although the ultraviolet rays are irradiated from the side of the ink droplets, the present invention is not limited to this. For example, as shown in FIG. By irradiating ultraviolet rays from the obliquely downward direction of the ink droplets in this way, a thin film can be formed on the lower side of the ink droplets, so that the spread of ink when landing on the printing paper P is more efficiently suppressed. be able to. In addition, as shown in FIG. 11, when irradiating ultraviolet rays from the obliquely downward direction of the ink droplet, it is desirable that the light source unit is composed of only a large number of ultraviolet LEDs 15a without providing the gradient index lens array 15b. .

  Also, as shown in FIG. 11, when the ink droplets are irradiated with ultraviolet rays from an obliquely downward direction, some of the ultraviolet rays L1 emitted from the ultraviolet LED 15a are emitted from the ink heads 10a to 10d. Since the reflected ultraviolet rays L1 reflected by the reflecting member 14 provided on the ink can be applied to the ink after landing on the printing paper P, the ultraviolet rays for fixing the ink can be irradiated at the same time. .

  Moreover, in the said embodiment, although the light source part 15 was comprised from many ultraviolet LED15a arrange | positioned at 1 row and the gradient index lens array 15b, the structure of a light source part employ | adopts another structure. You may do it. For example, as shown in FIG. 12A, the light source unit 80 may be configured by one ultraviolet LED 81 and a fiber light guide unit 82 in which a large number of optical fibers are bundled. The fiber light guide unit 82 is configured such that one end of many optical fibers is combined into one and the other end is formed in a fan shape.

  Then, one end face that is collected is optically connected to the ultraviolet LED 81, and the end face that is formed in a fan shape is a height between the ink head unit 10 and the printing paper P (paper transport unit 20). Arranged. FIG. 12B is a view of the ink heads 10a and 10b and the light source unit 80 shown in FIG.

  As shown in FIG. 12 (b), by forming one end of the fiber light guide portion 82 in a fan shape, the emission end face of the ultraviolet light can be formed thin, so that the array of ultraviolet LEDs 15a is formed as in the above embodiment. The space between the ink head unit 10 and the printing paper P (paper transport unit 20) can be made narrower than the arrangement. In other words, even when the space between the ink head unit 10 and the printing paper P (paper transport unit 20) is narrow, the light source unit 80 can be disposed, and the ink droplets can be appropriately irradiated with ultraviolet rays. it can. In addition, since the number of ultraviolet LEDs can be reduced, the cost can be reduced and the power consumption can be suppressed.

  As a method of irradiating ultraviolet rays as parallel light, in the above description, an optical material (glass or plastic) such as a gradient index lens array or an optical fiber is used to process the ultraviolet rays into parallel light. Not only this but the method of utilizing reflection of light is also considered. Specifically, as shown in FIG. 13, a light source unit 90 is configured by one ultraviolet LED 91 and a parabolic mirror 92, and parallel light is generated by installing the ultraviolet LED 91 at the focal position of the parabolic mirror 92. can get. In the method using reflection, an effect of reducing the attenuation of ultraviolet rays due to the transmission of the material can be obtained.

  Further, in the inkjet printer 1 of the above embodiment, the intensity of ultraviolet rays irradiated to the ink knob may be changed according to the type of the printing paper P. Specifically, as shown in FIG. 14, a paper type information acquisition unit 54 that acquires information on the type of printing paper P is provided in the control system 50, and the light source control unit 53 is acquired by the paper type information acquisition unit 54. The magnitude of the drive voltage supplied to the ultraviolet LED 15a may be controlled based on the information on the type of printing paper P. As a method for controlling the driving voltage according to the type of printing paper P, for example, for a straw paper that easily absorbs ink, a relatively high driving voltage is set for plain paper that does not absorb ink more easily than straw paper. Also, for a coat that absorbs less ink than plain paper, the drive voltage is set to be relatively lower than that of plain paper, or the drive voltage is set to zero so that ultraviolet light is not irradiated. Good. The driving voltage corresponding to the type of printing paper P may be set in advance in a table, for example.

  Moreover, in the inkjet printer 1 of the said embodiment, you may make it change the intensity | strength of the ultraviolet-ray irradiated to an ink pick according to the kind of ink. Specifically, as shown in FIG. 14, an ink type information acquisition unit 55 that acquires information on the type of ink is provided in the control system 50, and the light source control unit 53 acquires the ink acquired by the ink type information acquisition unit 55. The magnitude of the drive voltage supplied to the ultraviolet LED 15a may be controlled based on the type information. As a method for controlling the drive voltage according to the type of ink, for example, the drive voltage may be set lower as the viscosity of the ink is higher. For ink having a particularly high viscosity, the driving voltage may be set to zero and ultraviolet irradiation may not be performed. The drive voltage corresponding to the type of ink may be set in advance in a table, for example. Further, the ink viscosity may be acquired instead of the ink type information.

  Further, in the inkjet printer 1 of the above embodiment, the intensity of ultraviolet rays irradiated to the ink knob may be changed according to the temperature of the ink and the environmental temperature. Specifically, as shown in FIG. 14, a temperature information acquisition unit 56 that acquires ink temperature and environmental temperature information is provided in the control system 50, and the light source control unit 53 is acquired by the temperature information acquisition unit 56. You may make it control the magnitude | size of the drive voltage supplied to ultraviolet-ray LED15a based on temperature information. As a method for controlling the drive voltage according to the temperature information, for example, the higher the ink temperature or the environmental temperature, the lower the ink viscosity. Therefore, the drive voltage may be set higher. When the ink temperature or the environmental temperature is low and the ink absorption hardly causes a problem, the drive voltage may be set to zero so that the ultraviolet irradiation is not performed. The drive voltage corresponding to the temperature information may be set in advance in a table, for example.

  As described above, by controlling the driving voltage in accordance with the type of printing paper P, the type of ink, or temperature information, it is possible to further optimize the absorption of ink on the printing paper P and to irradiate useless ultraviolet rays. By suppressing the power consumption, it is possible to reduce power consumption.

  In the above description, the intensity of the ultraviolet rays applied to the ink droplets is controlled by controlling the driving voltage of the ultraviolet LED 15a. However, the present invention is not limited to this. For example, the intensity of the ultraviolet rays using a diaphragm or a filter is used. May be controlled.

  Further, in the inkjet printer 1 of the above embodiment, the ink ejection control unit 52 ejects ink from each of the ink head units 10 a to 10 d based on the ink viscosity information acquired by the ink type information acquisition unit 55. The timing may be controlled. Specifically, for example, the higher the ink viscosity, the faster the ink ejection timing (shortens the ink ejection interval).

  This is because the ink ejection timing and the ultraviolet irradiation timing are more accurately matched, and the higher the ink viscosity, the more difficult the ink is ejected from the ejection port 12. By controlling the ink ejection timing as described above, it is possible to appropriately irradiate ultraviolet rays with ink droplets.

  Moreover, although the inkjet printer 1 of the said embodiment performs single-sided printing, it is good also as an inkjet printer which performs double-sided printing. In double-sided printing, there is a problem of show-through due to ink absorption, so that a more remarkable effect can be obtained.

  In the ink jet printer 1 of the above-described embodiment, the light source unit 15 is provided on the upstream side and the downstream side of the ink head unit 10. You may make it provide the light source part 15 along.

  In the ink jet printer 1 of the above embodiment, the two light source units 15 are provided for the ink head unit 10. However, the present invention is not limited to this, and each of the ink heads 10 a to 10 d of the ink head unit 10. Alternatively, one or two light source units may be provided.

DESCRIPTION OF SYMBOLS 1 Inkjet printer 10a-10d Ink head 10 Ink head part 11 Ink chamber 12 Discharge port 13 Light shielding member 14 Reflective member 15 Light source part 15a Ultraviolet LED
15b Refractive index distribution type lens array 20 Paper transport unit 30 Paper feed unit 40 Paper discharge unit 50 Control system 51 Paper transport control unit 52 Ink discharge control unit 53 Light source control unit 54 Paper type information acquisition unit 55 Ink type information acquisition unit 56 Temperature Information acquisition unit 60 Reflective mirror 70 Fixing light source unit 80 Light source unit 81 UV LED
82 Fiber light guide

Claims (6)

An ink ejection unit that ejects photocurable ink toward the recording medium;
An ink discharge apparatus comprising: a light irradiation unit configured to irradiate light to the photocurable ink before the photocurable ink discharged from the ink discharge unit reaches the recording medium. .   The ink ejection apparatus according to claim 1, wherein the light irradiation unit irradiates light from a direction perpendicular to a discharge direction of ink discharged from the ink discharge unit. The ink discharge section discharges the photocurable ink at a predetermined interval;
The ink ejection device according to claim 1, wherein the light irradiation unit controls the light emission timing based on the ejection timing of the photocurable ink from the ink ejection unit. .   4. The ink ejection apparatus according to claim 1, wherein the light irradiating unit irradiates the light curable ink with the light from two opposing directions. 5.   The light irradiation unit includes a light source that emits the light in one of the two opposing directions, and a reflection unit that reflects the light emitted from the light source in the other direction. The ink discharge apparatus according to claim 4.   6. The ink ejection apparatus according to claim 1, wherein a light-shielding member that shields the light is provided around a discharge port of the photocurable ink of the ink ejection unit.